In this article, we are going to **write a Prime Number Program In C**.

We will make this program in the following way -:

- Prime Number Program In C
**Using For Loop** - Prime Number Program In C
**Using While Loop** - Prime Number Program In C
**Using Do While Loop**

To make this program, we will use the following concept given below.

If you do not know about these topics well, then you may not understand this program, so you should know about them in detail from the link given above.

Now without wasting time let’s start programming.

Page Contents

## Prime Number Program In C Using For Loop

### Algorithm

- Program start
- Declare Variable
- Loop start
- Check if condition
- Desplay result According to Condition
- Program End

### Program

```
//C Program to check prime number Using For loop
#include <stdio.h>
int main()
{
int n, i, count = 0;
printf("Enter a number to check prime number or not : ");
scanf("%d",&n);
for(i=2; i<n; ++i)
{
// check for non prime number
if(n%i==0)
{
count=1;
break;
}
}
if (count==0)
printf("%d is a prime number.",n);
else
printf("%d is not a prime number.",n);
}
```

### Output

```
Enter a number to check prime number or not : 5
5 is a prime number.
```

## Prime Number Program In C Using While Loop

### Program

```
//C Program for Prime Number Using While Loop
#include <stdio.h>
int main()
{
int n, i = 2, count = 0;
printf("Enter number to check prime number or not : ");
scanf("%d",&n);
while(i<n)
{
// check for non prime number
if(n%i==0)
{
count=1;
break;
}
i++;
}
if (count==0)
printf("%d is a prime number.",n);
else
printf("%d is not a prime number.",n);
}
```

### Output

```
Enter number to check prime number or not : 17
17 is a prime number.
```

## Prime Number Program In C Using Do While Loop

### Program

```
//C program to check prime number using do while loop
#include <stdio.h>
int main()
{
int n, i = 2, count = 0;
printf("Enter a number to check prime number or not : ");
scanf("%d",&n);
do
{
// check for non prime number
if(n%i==0)
{
count=1;
break;
}
i++;
}while(i<n);
if (count==0)
printf("%d is a prime number.",n);
else
printf("%d is not a prime number.",n);
}
```

### Output

```
Enter a number to check prime number or not : 9
9 is not a prime number.
```

## Conclusion

So friends, in this article, we have written **a Prime Number Program In C** In this ways.

- Prime Number Program In C Using For Loop
- Prime Number Program In C Using While Loop
- Prime Number Program In C Using Do While Loop

If you have difficulty to understand any program or have any doubts or questions, then tell me in the comment below.